Docking of a single phage lambda to its membrane receptor maltoporin as a time-resolved event |
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Authors: | Gurnev Philip A Oppenheim Amos B Winterhalter Mathias Bezrukov Sergey M |
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Institution: | Laboratory of Physical and Structural Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA. |
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Abstract: | We have been able to observe the first step in bacteriophage infection, the docking of phage lambda to its membrane receptor maltoporin, at the single-particle level. High-resolution conductance recording from a single trimeric maltoporin channel reconstituted into a planar lipid bilayer has allowed detection of the simultaneous and irreversible interaction of the phage tail with all three monomers of the receptor. The formation of a phage-maltoporin complex affects the channel transport properties. Our analysis demonstrates that phage attaches symmetrically to all three receptor monomers. The statistics of sugar binding to the phage-receptor complex on the side opposite to phage docking show that the monomers of maltoporin still bind sugar independently, with the kinetic constants expected from those of the phage-free receptor. This finding suggests that phage docking does not distort the structure of the receptor, and that the phage-binding regions are close to, but do not overlap with, the sugar-binding domains of the maltoporin monomers. However, ion fluxes through the pores of maltoporin in the phage-receptor complex share a new common pathway. We expect that the present study contributes to the current needs for structural information on the functional complexes involved in intercellular recognition. |
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Keywords: | p f u plaque-forming units |
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